The U.S. intelligence agency said that a phonetic analysis of his speech suggested this conclusion.

Broz - who came to power in the post-WW2, single-party communist Yugoslavia, and remained president until his death in 1980 - was officially of mixed Croat-Slovenian heritage.

But the paper says that the manner in which he spoke "Serbo-Croatian" - allegedly his mother tongue, but spoken with a foreign accent - meant that his true native language, "or at least one closer to him than Serbo-Croatian," was either Russian or Polish.

The authors of the lengthy analysis conclude that it would be "logical to assume" that the controversial leader was either Russian or Polish, but stress that his true identity can only be hypothesized - but that it "certainly was not Yugoslav."

They went on to assert that his non-Yugoslav origins were the reason for his "impartiality and success in solving the various problems and conflicts of ethnic groups in Yugoslavia."

The speech that was analyzed dates back to 1977, Belgrade-based Politika and Mondo media outlets are quoting the document on Monday, adding that "any further investigation of Tito's true identity would only serve academic purposes."